Channel Capacity Limits of Cognitive Radio in Asymmetric Fading Environments

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Cognitive radio technology is an innovative radio
design concept which aims to increase spectrum utilization by exploiting
unused spectrum in dynamically changing environments.
By extending previous results, we investigate the capacity gains
achievable with this dynamic spectrum approach in asymmetric
fading channels. More specifically, we allow the secondary-toprimary
and secondary-to-secondary user channels to undergo
Rayleigh or Rician fading, with arbitrary link power. In order
to compute the capacity, we derive the distributions of ratios
of Rayleigh and Rician variables. Compared to the symmetric
fading scenario, our results indicate several interesting features
of the capacity behaviour under both average and peak received
power constraints. Finally, the impact of multiple primary users
on the capacity under asymmetric fading has also been studied.

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Fields of Research::290000 Engineering and Technology::291700 Communications Technologies::291710 Radio communications and broadcasting not elsewhere classified